Savidge, W., Bell, R. J., Toler, S. K., & Short, R. T. (2010, June). Sediment-water exchange on the Georgia mid-shelf. In GEOCHIMICA ET COSMOCHIMICA ACTA (Vol. 74, No. 12, pp. A915-A915). THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND: PERGAMON-ELSEVIER SCIENCE LTD.
In permeable sediments, exchange of near-interface porewater constituents with the overlying water is driven primarily by advective movement of water through the sand matrix. As part of BOTTOMS-UP, we have developed novel independent and non-invasive methods for time series sampling of porewater constituents and for estimation of time and depth-dependent fluid exchange rates within sediments (Figures 1). We have combined these data within advection-diffusion models to make realistic estimates of in situ respiration and methanogenesis rates in permeable shelf sands.
Advection rates are derived from modelling propagation of temperature changes in the overlying water into the sediment. Porewater concentrations of metabolically active gases (O2, CO2, N2, and CH4) are obtained by repeatedly profiling the sediment with a newly developed sampling probe for an underwater Membrane Inlet Mass Spectrometer uMIMS.